The landmark lawsuit was the first to go to trial alleging a glyphosate link to cancer.

The claimant, groundsman Dewayne Johnson, was diagnosed with non-Hodgkin's lymphoma in 2014. His lawyers said he regularly used a form of RangerPro while working at a school in Benicia, California.

The Californian jury said Monsanto should have warned users about the dangers of its Roundup and RangerPro weedkillers.

Mr Johnson is among more than 5,000 similar plaintiffs across the US.

Glyphosate is the world's most common weedkiller. The California ruling could lead to hundreds of other claims against Monsanto.

A Bayer spokesperson told the BBC on Saturday that the two companies operated independently. In a statement the company said: "Bayer is confident, based on the strength of the science, the conclusions of regulators around the world and decades of experience, that glyphosate is safe for use and does not cause cancer when used according to the label."

Monsanto said it intends to appeal against the verdict.

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What is glyphosate and is it dangerous?

Glyphosate was introduced by Monsanto in 1974, but its patent expired in 2000, and now the chemical is sold by various manufacturers. In the US, more than 750 products contain it.

BBC North American correspondent James Cook reported that in California - where a judge recently ruled that coffee must carry a cancer warning - the agriculture industry sued to prevent such a label for glyphosate, even though the state lists it as a chemical known to cause cancer.